Apparatus for ultra-high vacuum in situ thin film studies

ABSTRACT

A thin film fabricating and test apparatus has a substrate holder cart positioned on a pair of tracks within a tubular vacuum system. Feed through drive units operate to move the cart to positions adjacent deposition units and test units within the vacuum system. A second drive unit positions the cart and moves masks and test contacts to a position adjacent substrate. A third drive unit positions deposition control shutters adjacent the substrate.

[451 Nov. 28, 1972 United States Patent Rut et a].

[54] APPARATUS FOR ULTRAJ'IIGH 10/1964 Harshberger..........104/l 19 XVACUUM IN SITU THIN FILM STUDIES 9/1969 Bukkila et 18/49 X [72]Inventors: Franz X. Rut, Kettering; Wayne R.

3,152,559 3,469,560 3,473,510 lO/l969 Sheng et al. 1 18/495 Chase,Dayton; Raymond A. Preil, Fairbom, all of Ohio [73] Assignee: The UnitedStates of America as m m M u m m m m m wk mm mm 2 m z w 1 m 9 a mmmrepresented by the Secretary of the Air Force pparatus has a suboldercart positioned on a pair of tracks within a tubular vacuum system. Feedthrough drive units strate h [22] Filed: May 13, 1971 [21] App]. No.:143,080

wAmAm wm 8 am e m fl fi tye RSV m e oum mmm m ww m mw n m oemmf mm ntlom. m m w m .m m wt 0 mianm... 8 mm mt M t mC mmemm V e .m mm wmdwm m dE ofimmm 58 3 5 myw 8 ww mm m w jm mm lnuo "n l 9 M 8 ell m m mm m IO ds m UmF HUN UUU adjacent the substrate.

4Ciains,l8DrawingFigures [56] References Cited ,536Ma1oney....................104/119 APPARATUS FOR ULTRA-HIGH VACUUM INSITU THIN FILM STUDIES BACKGROUND OF THE INVENTION When testing advancedelectronic devices, it is difficult to obtain the basic deviceproperties so as to gain a more quantitative understanding of the basicphysical principles governing the device. This is due to the fact thatit is impossible to separate the basic device properties from theeffects due to contamination.

BRIEF SUMMARY OF THE INVENTION According to this invention, an apparatusis provided for fabricating test samples, for performing surfacetreatment and for measuring selected properties without removing thesample from the vacuum chamber. A stainless-steel tube has a transportsystem, supported therein on spaced supports, which is used to move atest sample from stage to stage. The operations performed at the variousstages are determined by the particular test sample being constructedand tested. For example, operating stages could be provided for maskingthe substrate and depositing thin-films, for surface treating thedevice, and a stage where electrical contacts are made with the sampleso that various tests can be made on the sample. The apparatus is madeof materials such as stainless steel, titanium, tantalum and boronnitride so that the apparatus can be baked under vacuum conditions to450 C. Also, the apparatus is constructed to permit vacuum conditions ofthe order of 10- Torr. The apparatus is made up of units which can beattached together in various combinations to perform differentoperations.

IN THE DRAWINGS FIG. 1 is a schematic diagram partially in block form ofa fabrication and test apparatus according to the invention.

FIG. 2 is a top view of the drive section for the device of FIG. 1.

FIG. 3a is an isometric view of the transport assembly for the device ofFIG. 1.

FIG. 3b is an enlarged isometric view of a portion of the device of FIG.30.

FIG. 4 is an end view of the cart for the device of FIG. 3. g

FIG. 5 is a back view of the device of FIG. 4.

FIG. 6 is a top view of the device ofFIG. 4.

FIG. 7 is a schematic view of the cart device assembly for the device ofFIG. 3.

FIG. 8 is an enlarged isometric view of the shaft couplers for thedevice of FIG. 3.

FIG. 9 is an enlarged view of the mask and indexing mechanism for thedevice of FIG. 3.

FIG. 10 is an enlarged top view of the shutter mechanism for the deviceof FIG. 3.

FIG. 11 is an enlarged partially cut away end view of the test read outstation for the device of FIG. 3.

FIG. 12 is the bottom view of a substrate as placed in the cart forprocessing in the device of FIG. 1.

FIG. 13 is the top view of the mask used for deposition of silver on thesubstrate of FIG. 12.

FIG. 14 is the bottom view of the substrate of FIG. 12 with silverdeposited thereon.

FIG. 15 is the top view of the mask used for deposition of cesium on thesubstrate of FIG. 14.

FIG. 16 is the bottom view of the substrate of FIG. with silver andcesium deposited thereon.

FIG. 17 is a schematic diagram of the test station for the device ofFIG. 1.

DETAILED DESCRIPTION OF THE INVENTION Reference is now made to FIG. 1 ofthe drawing wherein reference number 10 shows an electronic devicefabricating and testing apparatus, made up of a plurality of individualtubular sections 12, 14 and 16. Although three sections are shown, moreor fewer sections, or sections different from those shown can be used.

Section 12 has a cesium deposition unit shown schematically at 17 and atest section shown at 19. Units 22, 23, and 24 have transparent windows,not shown. The unit 21 and window 23 are unused in this system. Window22 is used for viewing and window 24 is used to illuminate the testdevice to obtain test data.-

Section 14 has three drive units 27, 28 and 29 as shown in FIG. 2. Thedrive units 27, 28 and 29 may be conventional drive units, for example,magnetic drive units. Unit 31 is a silver deposition unit and unit 32has a viewing window. In section 14 units 34, 35 and 36 are unused,however, one of these could be used for vacuum testing.

Section. 16 has a roughing vacuum pump 38 and an ion vacuum pump 40.Other vacuum pumps can be provided as needed.

When the apparatus shown in FIG. 1 is baked out, parts that will notwithstand the baking temperature, such as drive units 27, 28 and 29, areremoved.

FIGS. 3a and 3b show the test sample transport system 42 used in thedevice of FIG. 1. Portion 44 of the transport system is positionedwithin tubular section l2,and portion 46 is positioned within tubularsection 14. All of the parts of the system are made of stainless steelunless otherwise specified.

The transport system 42 is supported within the tubular sections 12 and14 by means of support plates 48. The plates are positioned by means ofadjustable support legs 49 which are threaded into tantalum leg blocks51.

A pair of tracks 52 and 53 extend the length of units 12 and 14 with theends of one section abutting the ends of the other section. Tracks 52and 53 are placed on one side of the system so as to leave the otherside free for use of the equipment used in fabricating and testing thetest device.

A cart 55, shown in greater detail in FIGS. 4-6, rides along the tracksin cantilever fashion and is held on the tracks by its weight. A pair ofpulley-like wheels 57 and 58 are secured to cart side plate 64 and rideon circular track 52 and serve to guide the cart. A flat wheel 59 isalso secured to side plate 64 and rides on the under side of track 53.The cart and wheels are made of titanium to reduce weight.

The cart is moved along the tracks by means of a The cable 60 passesaround cable drive wheel 73, which is driven by drive unit 28, andaround idler pulleys 75 and 76. Pulley 75 is spring loaded, as shown inFIG. 7, to allow for changes in cable length during bake out.

Three shafts 78, 79, and 80 extend the length of the two sections andact to operate the processing equipment at the various stations. Theshafts from portion 44 are coupled to the shafts from portion 46 by slipapart couplings 81, as shown in FIG. 8. Shafts 78 and 79 are operated bymotion rod 82 which is driven by drive unit 29 to move mask holders 84and indexing rods 89 and contact bar 87 into position adjacent the testsample and index bar 65. Shaft 79 is moved by cam 90 and in turn movesshaft 78 through shaft coupler 92. Shaft coupler 92 was replaced bysector gears in a later model.

The shutter shaft 80 is gear driven from shaft 94 which is driven. bydrive unit 27. I

The shutter mechanism is shown in greater detail in FIG. 10. The shutter94 is held .closed by a spring 95 secured to support plate 48. A monitorshutter 97 is secured to shaft 80 at 96 and is opened by the initialmovement of shaft 80 to permit control of the evaporation rate by aconventional evaporation monitor sensor, not shown. Continued rotationof shaft 80 causes arm 99, which is secured to shaft 80, to engage a pin101 secured to one of the shutter supports 103 to which shutter supportarms 104 are also attached. Movement of pin 101 acts to open thesubstrate shutter 94. The shutter supports 103 are supported on shaft 80by means of rotatable boron nitride bushings 105.

Electrical contact is made with the test sample by means of gold fuzzbuttons 107 on a boron nitride block 108. Leads connected to the fuzzbuttons 107 pass out through unit 19 in FIG. 1.

g In the operation of the apparatus, a substrate such as shown in FIG.12, is secured by the tantalum clips 71 in the substrate holder 67 ofthe substrate cart 55. The substrate shown in FIG. 12 has an aluminumstrip 111, aluminum oxide insulators 113 and gold contacts 115 thereon.The substrate shown in FIG. 12 can be produced external to the systemand then placed on the substrate can 55 for additional processing, or itcould be produced within the apparatus by providing additional operatingstations. After the substrate, as shown in FIG. 12, is secured to thecart 55, the system is sealed and evacuated and baked to outgas all ofthe parts. Drive unit 28 is then operated to position the cart adjacentthe unit 31. Drive unit 29 is then operated to engage the indexing rod86 into engagement with the center notch 66 in indexing bar 65 and tomove the mask holder 84 with a mask such as shown in FIG. 13 adjacentthe substrate.

Drive unit 27 is then operated to permit monitor shutter 97 andsubstrate shutter 94 to move into position over the mask holder. Thesilver deposition unit is then energized and the monitor shutter 97 isopened to set the deposition rate in the conventional manner. When theproper deposition rate is established, the substrate shutter 94 isopened to deposition of silver strips 117 onto the substrate to thedesired thickness in a pattern as shown in FIG. 14. The shutters arethen returned to their position over the mask holder and the silverdeposition unit is de-energized. When silver Cart drive unit 28 is thenoperated to move the cart adjacent the cesium deposition unit 17, wherecesium is deposited with a conventional cesium gun in a like operationexcept that cesium is deposited through one aperture at a time in themask of FIG. 15. The cart is positioned for separate deposition ofcesium layers 1 19 by having the index rod'86 engage the separate'slots66 in the index bar 65. When cesium deposition is completed, the cart 55is moved adjacent the test unit 19. Operation of drive 29 moves indexrod 86 into engagement with the center slot 66 of index bar 65and movesthe fuzz button contacts 107 into engagement with substrate contacts115, shown in 17. The unit is then illuminated through window 24, asshown schematically in FIG. 17 and the desired tests may be made on thetest device.

There is thus provided a device for fabricating a test sample and formeasuring selected properties without removing the test sample from thevacuum chamber.

While only one system for fabrication and test has been described, moreand differentfabricating and test units could be used for making andtesting different test devices than that described. Also, othermaterials than those described could be usedin the apparatus. Any highvacuum compatible materials which meet the mechanical requirements maybe used, for example, oxygen free hard copper could be used for many ofthe parts.

We claim:

1. The combination, comprising: a tubular vacuum system includingdeposition and testing chambers; a plurality of spaced supports disposedwithin said tubular system; a first bar member, having a rectangularcross section, secured to said space supports and forming a first carttrack; a second bar member, having a circular cross section, secured tosaid spaced supports and forming a second cart track; said bar membersbeing vertically and horizontally spaced from one another; a cartadapted to run on said first and said second cart tracks; said cartincluding a test specimen support and means for supporting said' cartand test specimen support in cantilever relation on said first and saidsecond cart track; and means for moving the cart along said tracks andthrough said chambers.

2. In the combination recited in claim 1, wherein means for supportingthe cart and test specimen in cantilever relation on said first and saidsecond cart track includes a cart side member with a first and a secondpulley type wheel engaging the bar member with a circular cross sectionand a third wheel engaging, the under side of the bar member with therectangular cross section.

3. In the combination as recited in claim 1 wherein are provided maskand shutter mechanisms and feed through drive means for positioning saidmasks and shutter mechanisms adjacent the test specimen to control thedeposition of active material to the test specimen.

4. In the combination as recited in claim 3 wherein the active materialis photoelectric material-and the means for testing the specimenincludes means for making predetermined electrical Contact with the testspecimen and means for illuminating the test specimen.

1. The combination, comprising: a tubular vacuum system includingdeposition and testing chambers; a plurality of spaced supports disposedwithin said tubular system; a first bar member, having a rectangularcross section, secured to said space supports and forming a first carttrack; a second bar member, having a circular cross section, secured tosaid spaced supports and forming a second cart track; said bar membersbeing vertically and horizontally spaced from one another; a cartadapted to run on said first and said second cart tracks; said cartincluding a test specimen support and means for supporting said cart andtest specimen support in cantilever relation on said first and saidsecond cart track; and means for moving the cart along said tracks andthrough said chambers.
 2. In the combination recited in claim 1, whereinmeans for supporting the cart and test specimen in cantilever relationon said first and said second cart track includes a cart side memberwith a first and a second pulley type wheel engaging the bar member witha circular cross section and a third wheel engaging the under side ofthe bar member with the rectangular cross section.
 3. In the combinationas recited in claim 1 wherein are provided mask and shutter mechanismsand feed through drive means for positioning said masks and shuttermechanisms adjacent the test specimen to control the deposition ofactive material to the test specimen.
 4. In the combination as recitedin claim 3 wherein the active material is photoelectric material and themeans for testing the specimen includes means for making predeterminedelectrical contact with the test specimen and means for illuminating thetest specimen.